It refers me back to my machine Roll Out The Barrel, and the questions I was asking about it a year and a bit ago. The case although very substantial with a heavy metal door to the rear is clearly a conversion. It has two coin entries accepting old pennies and small tokens each of which play the machine. The pennies all track to the cash box, it only pays out tokens.
The mechanism is clock controlled and there is a fourth reel to the left which automatically shows you the value of your winnings.
The machine pays out as each reel stops - it doesn't wait until all three have stopped, likewise the fourth reel advances as each payout occurs.
It's my intention to dispose of this probably at Coventry so for the sake of accuracy in the catalogue any further information about this one would be helpful.